Flexible load transfer device



Nov. 11, 1941. A. E. BRlcKMAN ErAL 2,262,090

FLEXIBLE LOAD TRANSFER DEVICE Filed oct. i4, 1959 ,Q4/V E EEK/(MQW ma650/965 4. ,64 W50/V,

Patented Nov. 11, 1941 FLEXIBLE OAD TRANSFER DEVICE Alan. E. Brickman,Rostravor Township, Westmoreland County, and George A. Gleason,Worcester, Pa., assignors to The American Steel and Wire Company of NewJersey, a corporation of New Jersey Application October 14, 1939,ASerial No. 299,564

2 Claims.

The present invention relates to a load transfer device for transversejoints in concrete roadways, walks and the like.

An object of the invention is to provide a load transfer device across ajoint in a concrete roadl way and pavement having complementary unitsmovable relative to each other upon the eXpansion and contraction of theroadway or pavement.

A further object is to provide a load transfer device which, in additionto having great resistance against shear, provides flexibility in the`invention in position in the concrete roadway or pavement;

Figure 2 is a section on line II-II off Figure 1-;

Figure 3 is a section on line IlI--III of Figure l; and,

Figure 4 is a detailed perspective of one of the laminated dowelmembers.

Referring more particularly to the drawing, the load transfer device, ofthe present invention,

includes two complementary members or units of identical constructiondesignated generally at A and B.

Each unit forming one-half of the load transfer device comprises plates2 and 3 of identical construction, maintained in spaced `relation toeach other by a laminated structure 4. Each of the plates 2 and 3 hasone of its ends bent laterally, as indicated at 5, from its normalhorizontal plane so as to provide a good anchorage within the concreteslab sections.

The laminated structure 4, of each complementary unit, includesstrip-like members indicated at 4a, 4b and 4c in frictional contact onlywith each other throughout the entire length of said laminatedstructure. The ends of said striplike members 4a., 4b and 4c are welded,in any conventional manner, as indicated at IB to plates I5 so that theends of said laminated structure projecting beyond the flange I8 ofplates I5 form a laminated dowel 4d.

The outside members 4a and 4c of each laminated structure may be Welded,if desired, in any conventional manner to said plates 2 and 3. Theintermediate members 4b of each 'laminated structure is provided, uponone face, with a serrated surface or rack 'I overwhich is adapted toride an inwardly pressed lip or pawl member 8 formed on each of plates 9constituting a partof the housing within which said dowel 4d slides. Theinwardly pressed lip or pawl 8 provides a shallow stiff sharp edge ofsuicient height to assure racked engagement even though some warpyagemay be present due to forming of the plate 9. Finger grip catches I2 areprovided on the plates 9 whereby the inwardly pressed lip or pawl 8 iscapable of being lifted so as to disassemble the unit, i'f necessary.

The'plates 9 are of identical construction and include laterallyextending flanges Il) and flanges I4, the latter flanges forming, incombination with the laminated structure and plates 2 and 3, dowelreceiving pockets of a depth not less than the length of said dowel 4dwithin which the outside horizontal edges of the laminated dowelstructure 4d is in slidable engagement with the horizontal edges 20 ofsaid dowel receiving Dockets.

The plates 9 have a free movement with respect to the plates 2 and 3 astheyare not welded thereto but are secured at flange I4, by welding, tothe ends of the laminateddowel members4a, 4b `and 4c, thus providing,due to the resiliency of the metal, spring pawl contact on the rack onsaid dowel members.

The plates I5 are provided with laterally extending flanges I8 whichcooperate with the flanges I0, of plate 9, to vertically andhorizontally align the units in relation to the joint.

The joint assembly is usually supported, during installation, by a`bulkhead (not shown) and pinned to the subgrade to withstand the flowof concrete used in forming the roadway or pavement slabs or sectionsafter which the bulkhead plate or pins are removed and the jointassembly appears as shown in Figure 1.

In assembling the trans-load device, the units A and B are positioned`and arranged as shown in Figure 2 of the drawing so that the laminateddowel 4d, of unit A, extends through an aperture formed in aconventional type joint filler I9 into the dowel receiving pocket inunit B, while the laminated dowel 4d, of unit B, extends through thesame aperture in said filler I6 and into the dowel receiving pocket ofunit A, thereby providing a load transfer device having a laminateddowel construction which will offer great resistance to shear and willprovide suicient flexibility to compensate for warpage of the pavementslabs or sections. Warpage cf a pavement or roadway slab may be apermanent condition which takes place When the concrete sets or hardensand is due to a difference in the rate of setting between the top andbottom portion of the slab, caused primarily by the difference' in thetemperature between the top and bottom portion thereof. This slabwarpage may also take place at any time after the concrete haspermanently set, due to sudden changes in temperature. For example,during extremely low temperatures a pavement slab or section iscontracted and should there be a sudden rise in temperature, due toexposure of the top surface of the concrete to heat or the sun, saidsurface of the slab will expand. in `advance of the bottom surface,thus'causing warpage of the slab section. By providing Ya constructionincluding a laminated `dowel construction, suitably welded to the plates9 and I5 and the spaced plates 2 and 3, it is obvious that such aconstruction will permit flexing of the joint to compensate for slabwarpage.

The cooperation between the pawl 8 and the rack 1, of the respectiveunits, provides a means for initially holding the component partsforming the load transfer device in proper position, upon the roadbed,until the concrete which is poured to form the slabs has set. After theload transfer device has become embedded in the concrete, thecooperative action of the pawl and rack, of the respective units, may beinoperative by shear Ythrough subsequent relative movement of theconcrete.

In our Patent No. 2,212,680, dated August 27, 1940, and entitled Loadtransfer device, there is disclosed a construction which is generallysimilar to that of the present invention. The present invention,however, differs therefrom in the employment of the .laminated dowelelements 4d, and in details of construction used in combinationtherewith.

While Vwe haveshown and described a specific embodiment of the presentinvention, it will be seen that We do not wish to be limited exactlythereto, since various modifications may be made without departing fromthe scope of the invention, as defined by the following claims.

We claim:

1. A load transfer device for adjacent concrete road slabs, comprising afiller positioned between the road slabs and having an openingtherethrough, a pair of like load transfer units disposed on oppositesides of said filler, each of said load transfer vunits having adowel-receiving pocket in alignment with the opening in said filler, adowel secured-to each of said load trans- -fer units and extendingthrough the opening in the filler and into the dowel-receiving pocket inthe other of said units, said dowels being reversed with respect to eachother and each comprising aplurality of superposed frictionallycontacting yelements slidably engaging the dowel-receiving pocketof theopposite load transfer unit and also the dowel secured to the latter,said dowel-receiving pockets being of a depth to closely embrace theupper and lower faces of the outer of the superposed frictionallycontacting elements of said dowels, and means for anchoring each of saidload transfer units in its respective concrete road slab.

2. A load transfer device for adjacent concrete road slabs, comprising afiller positioned between the road slabs and having an openingtherethrough, a pair of like load transfer units disposed on oppositesides of saidv filler, each of said load transfer units having adowel-receiving pocket in alignment with the opening in said filler, adowel secured to each of said load, transfer units and extending throughthe opening in the filler vand .into the dowel-receiving pocket; in theother of said units, said dowels being reversed to each other and eachcomprising a plurality of superposed frictionally contacting elementsslidably engaging the doWel-receiving pocket of the opposite loadtransfer unit and also the dowel secured to `the latter, means foranchoring each of said load transfer units in its respective concreteroad slab, and means for initially restraining the displacement of thedoWel of one load transfer unit from the doWel-receiving pocket ofthe-other of'said units.

ALAN E. BRICKMAN. GEORGE A. GLEASON.

